A) Field of the Invention
This invention relates to a new or improved prefabricated building panel designed for use in building structures of many different types including both residential and commercial.
B) Description of the Prior Art
The construction of buildings and in particular of residential buildings is labour intensive and involves numerous problems, among which may be mentioned quality control, high labour costs, lack of uniformity in design, as well as difficulties in erection. Transportation and materials handling costs can be high, and the construction is often hampered by adverse weather conditions.
The foregoing problems have been well recognized over the years and attempts have been made to overcome them in various ways. For example, the use of "factory built" housing involving the fabrication of modules or even complete structures in factory conditions for transportation and erection on site offers many advantages in terms of quality control, weather protection and the like, but lacks flexibility.
Other attempts at improving building practices have involved the provision of prefabricated insulated building panels of standard dimensions since it has been realized that by their use there is a potential to achieve great savings in labour and construction costs in the fabrication of various types of buildings. Examples of such building panels and prefabricated construction methods can be seen, for example, in the following U.S. patents:
U.S. Pat. No. 3,642,897--Weinrott PA1 U.S. Pat. No. 3,949,529--Porter PA1 U.S. Pat. No. 4,163,349--Smith PA1 U.S. Pat. No. 4,269,006--Larrow PA1 1. low purchase cost and finish cost PA1 2. rapid on-site erection PA1 3. capability of use by low-skilled labour PA1 4. good protection from the elements, and resistance to degradation by moisture, insects, etc. PA1 5. robustness so as to have good built-in resistance to rough handling PA1 6. the ability to accept virtually any type of exterior or interior finish PA1 7. lifetime durability with minimum maintenance PA1 8. easy adaptation to a wide variety of uses from one or not more than a small number of standard factory manufactured panel sizes PA1 9. a high degree of salvageability for reuse in the event of minor damage or improper cutting PA1 10. the ability for easy and quick replacement of damaged panels PA1 11. an absence of nails, staples or other such fasteners within the panel structure so that the panel can be readily cut to size without the use of specialized saws.
The foregoing represent but a small selection of prior proposals, but none of them achieves all of the features that are considered to be most desirable in building panels of this type, so that despite very many years of development, there are few such prefabricated insulated building panels being successfully employed commercially.
From a review of the requirements of the construction industry in manufacture and erection, the inventors have concluded that, to be successful, a prefabricated insulated building panel must provide most if not all of the following benefits:
Of all prior art panel structures, the one that comes closest to providing the above characteristics is that disclosed in U.S. Pat. No. 4,765,105 Tissington et al. The Tissington et al. panel has enjoyed a good measure of commercial success, having been employed in numerous residential, commercial and industrial applications and has been demonstrated to give superior insulating properties and significant cost savings as compared to more conventional building systems. The Tissington et al. structure comprises a stressed skin panel provided in standard sizes, typically 8 feet by 24 feet, having outer sheets of oriented strand board and an internal structure comprising a web of interlocking vertical and horizontal stud members cut from sheets of oriented strand board and creating cells that are filled with a polyurethane insulation that binds the structure and when hardened provides structural integrity and great stiffness. These panels have been shown to provide great strength and dimensional stability and are excellent for use in walls, floors and roofs in residential, industrial, commercial, institutional and agricultural buildings.
The Tissington et al. panels when integrated into buildings are easily finished by conventional methods. Drywall can readily be applied to interior walls or ceilings without the need for a vapour barrier (since the panel itself is impervious to water vapour) and exterior surfaces can easily be finished by applying thereto conventional siding or stucco. The panels have a continuous built-in header so that window and door openings can readily be cut out after manufacture, e.g. at the time of erection.
Because of the above discussed and other features, the Tissington et al. building panel achieves almost all of the above enumerated desirata. However applicants have now devised a prefabricated building panel which is even better adapted to fit a wide range of applications than the Tissington et al. panel and at the same time offers improvements in terms of weight, cost, and adaptability.